Method and device for allocating resource in wireless lan system, communication terminal method and communication terminal

ABSTRACT

Provided is a method and apparatus for allocating resources in a wireless local area network (WLAN) system, the method including determining a restricted access bandwidth (RAB) interval based on at least a bandwidth or a partial bandwidth among a plurality of bandwidths, and setting a restricted access window (RAW) of a time domain based on the 
     RAB interval.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/438,184, filed Apr. 23, 2015, which is a U.S. National Stage ofInternational Patent Application No. PCT/KR2013/009530, filed Oct. 24,2013, which claims priority to and the benefit of ProvisionalApplication No. 61/746,072, filed Dec. 26, 2012, Korean PatentApplication No. 10-2012-0118327, filed Oct. 24, 2012, and Korean PatentApplication No. 10-2013-0127273, filed Oct. 24, 2013, the entirecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a wireless local area network (WLAN)system and more particularly, a method and apparatus for allocatingresources in the WLAN system.

BACKGROUND ART

In general, development of wireless local area network (WLAN) technologyhas advanced in three directions.

One direction indicates technology for improving a transmission rate andincludes WLAN technology using a 60 gigahertz (GHz) band and WLANtechnology using a 5 GHz band. Another direction indicates wideband WLANtechnology using a frequency band under 1 GHz to extend coverage whencompared to conventional WLAN technology, and still another directionindicates technology for reducing link set-up time of a WLAN system.

Wideband WLAN technology is required to accommodate a remarkably largernumber of stations (STAs) than established WLAN technology.

Further, the wideband WLAN technology may need to support STAs withvarious types of services, such as, offloading terminals and sensorterminals, traffic types, and power saving demands.

Therefore, advancements are being made in a wideband WLAN system forreducing collisions in channel access and achieving efficient powersaving by grouping a plurality of STAs. Also, advancements are beingmade in the wideband WLAN system for using restricted resources such asa bandwidth, a time, and a power.

DISCLOSURE OF INVENTION Technical Solutions

According to an aspect of the present invention, there is provided aresource allocation method in a wireless local area network (WLAN)system, the method including determining a restricted access bandwidth(RAB) interval based on at least a bandwidth or a partial bandwidthamong a plurality of bandwidths, and setting a restricted access window(RAW) of a time domain based on the RAB interval.

The resource allocation method may further include inspecting a state ofa basic service set (BSS) including an access point (AP) and at leastone STA.

The resource allocation method may further include transmitting, to anSTA, information associated with the RAB interval and informationassociated with the RAW.

According to another aspect of the present invention, there is alsoprovided a communication method in a WLAN system, the method includingreceiving information associated with an RAB interval and informationassociated with an RAW, determining whether communication is availablein a frequency domain determined based on the RAB interval, andtransmitting, when communication is available in the frequency domain,data in a time domain determined based on the RAW.

According to still another aspect of the present invention, there isalso provided a resource allocation apparatus including an RAB intervaldeterminer to determine an RAB interval based on at least a bandwidth ora partial bandwidth among a plurality of bandwidths, and an RAW settingunit to set an RAW of a time domain based on the RAB interval.

The resource allocation apparatus may further include a state inspectorto inspect a state of a BSS including an AP and at least one STA.

The resource allocation apparatus may further include a communicator totransmit, to an STA, information associated with the RAB interval andinformation associated with the RAW.

According to yet another aspect of the present invention, there is alsoprovided communication terminal including a communicator to receiveinformation associated with an RAB interval and information associatedwith an RAW, and a controller to determine whether communication isavailable in a frequency domain determined based on the RAB interval,wherein the communicator transmits, when communication is available inthe frequency domain, data in a time domain determined based on the RAW.

Advantageous Effects

According to an aspect of the present invention, flexible usage of afrequency in temporally grouped windows is possible. As such, atransmission rate and performance in a wireless local area network(WLAN) system is improved without an additional effort.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a multi-bandwidth in a widebandwireless local area network (WLAN) system according to an exampleembodiment.

FIG. 2 is a diagram illustrating an example of a configuration of anInstitute of Electrical and Electronics Engineers (IEEE) 802.11 systemto which the present invention is applicable.

FIG. 3 is a diagram illustrating a configuration of a resourceallocation apparatus in a WLAN system according to an exampleembodiment.

FIG. 4 is a diagram illustrating a configuration of a communicationterminal in a WLAN system according to an example embodiment.

FIGS. 5 and 6 are diagrams illustrating examples of a resourceallocation method according to an example embodiment.

FIGS. 7A and 7B are diagrams illustrating examples of a configuration ofa duplication mode frame according to an example embodiment.

FIGS. 8A and 8B are diagrams illustrating examples of a configuration ofa duplication mode frame according to another example embodiment.

FIG. 9 is a flowchart illustrating an operation of a resource allocationmethod in a WLAN system according to an example embodiment.

FIG. 10 is a flowchart illustrating an operation of a communicationmethod in a WLAN system according to an example embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings. It is to beunderstood that the detailed description, which will be disclosed alongwith the accompanying drawings, is intended to describe the exemplaryembodiments of the present invention, and is not intended to describe aunique embodiment with which the present invention can be carried out.The following detailed description includes specific details in order toprovide a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without such specific details.

The following embodiments are achieved by combination of structuralelements and features of the present invention in a predetermined type.Each of the structural elements or features should be consideredselectively unless specified separately. Each of the structural elementsor features may be carried out without being combined with otherstructural elements or features. Also, some structural elements and/orfeatures may be combined with one another to constitute the embodimentsof the present invention. The order of operations described in theembodiments of the present invention may be changed. Some structuralelements or features of one embodiment may be included in anotherembodiment, or may be replaced with corresponding structural elements orfeatures of another embodiment. Specific terminologies hereinafter usedin the embodiments of the present invention are provided to assistunderstanding of the present invention, and various modifications may bemade in the specific terminologies within the range that they do notdepart from technical spirits of the present invention.

In some instances, known structures and devices are omitted or are shownin block diagram form, focusing on important features of the structuresand devices, so as not to obscure the concept of the invention. The samereference numbers will be used throughout this specification to refer tothe same or like parts.

The embodiments of the present invention may be supported by standarddocuments disclosed in at least one of wireless access systems, i.e., anInstitute of Electrical and Electronics Engineers (IEEE) 802 system, athird generation partnership project (3GPP) system, a 3GPP long termevolution (LTE) system, an LTE-Advanced system, and a 3GPP2 system.Namely, among the embodiments of the present invention, steps or partswhich are not described to clarify the technical features of the presentinvention may be supported by the above standard documents. Also, allterminologies disclosed herein may be described by the above standarddocuments.

The following technology may be used for various wireless access systemssuch as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), and single carrier frequencydivision multiple access (SC-FDMA). The CDMA may be implemented by theradio technology such as universal terrestrial radio access (UTRA) orCDMA 2000. The TDMA may be implemented by the radio technology such asglobal system for mobile communications (GSM)/general packet radioservice (GPRS)/enhanced data rates for GSM evolution (EDGE). The OFDMAmay be implemented by the radio technology such as IEEE 802.11 (Wi-Fi),IEEE 802.16 (WiMAX), IEEE 802-20, and evolved UTRA (E-UTRA). Althoughthe following description will be based on the IEEE 802.11 system toclarify description of technical features, it is to be understood thattechnical spirits of the present invention are not limited to the IEEE802.11 system.

FIG. 1 is a diagram illustrating a multi-bandwidth in a wideband WLANsystem according to an example embodiment.

A wideband WLAN system, for example, a WLAN system defined in the IEEE802.11ah standard, may support a multi-bandwidth. The multi-bandwidthmay include a first bandwidth having the lowest signal-to-noise ratio(SNR) and a second bandwidth that is two times greater than the firstbandwidth. In this instance, a value of the first bandwidth may be 1megahertz (MHz).

Referring to FIG. 1, the multi-bandwidth may include a bandwidth of 1MHz 110, a bandwidth of 2 MHz 120, a bandwidth of 4 MHz 130, a bandwidthof 8 MHz 140, and a bandwidth of 16 MHz 150. A frequency band of thewideband WLAN system may be less than or equal to 1 gigahertz (GHz).

Accordingly, “the multi-bandwidth may be expressed to include 1 MHz, 2MHz, 4 MHz, 8 MHz, and 16 MHz”.

For example, in FIG. 1, a frequency lower limit value 161 may be a valuebetween 700 MHz and 920 MHz, and a frequency upper limit value 163 maybe a value between 750 MHz and 930 MHz. As illustrated in FIG. 1, thebandwidth of 1 MHz 110 may be allocated throughout an entire channel,and remaining bandwidths, for example, the bandwidth of 2 MHz 120, thebandwidth of 4 MHz 130, the bandwidth of 8 MHz 140, and the bandwidth of16 MHz 150 may be allocated to only a portion of a section of the entirechannel.

For example, the bandwidth of 16 MHz 150 may be allocated between apredetermined frequency value 165 of FIG. 1 and the frequency upperlimit value 163. Referring to FIG. 1, eight channels are allocated tothe bandwidth of 2 MHz 120, four channels are allocated to the bandwidthof 4 MHz 130, and two channels are allocated to the bandwidth of 8 MHz140. However, allocation of channels as illustrated in FIG. 1 isprovided only as an example and thus, a number of channels and afrequency band may be configured using a variety of methods.

In the present specification, a transmission mode having a value of thebandwidth of 1 MHz 110 may be referred to as a 1 MHz mode, and atransmission mode having a value of the bandwidth of 2 MHz 120 may bereferred to as a 2 MHz mode. Also, transmission modes having values ofthe bandwidth of 4 MHz 130, the bandwidth of 8 MHz 140, and thebandwidth of 16 MHz 150 may be referred to as a 4 MHz mode, an 8 MHzmode, and a 16 MHz mode, respectively.

According to an example embodiment, the 1 MHz mode may indicate atransmission mode that maintains an orthogonal frequency divisionmultiplexing (OFDM) symbol structure and includes 32 subcarriers. Inthis instance, the 1 MHz mode may use a frequency domain repetitiontransmission method and thus, may have the lowest transmission rateamong bandwidths. In the 1 MHz mode, a signal may be transmitted to thefarthest distance since the 1 MHz mode has a relatively low SNR.

FIG. 2 is a diagram illustrating an example of a configuration of anIEEE 802.11 system to which the present invention is applicable.

The IEEE 802.11 system may include a basic service set (BSS) indicatinga basic configuration block. Referring to FIG. 2, a station (STA)-1 220and an STA-2 230 are described as BSS members. A communication apparatus210 may be an access point (AP) or a base station (BS).

In FIG. 2, a dotted line circle 211 indicating the BSS may be understoodto indicate a coverage area in which STAs or communication terminalsincluded in a corresponding BSS maintains communications. The coveragearea may be also referred to as a basic service area (BSA). When an STAis relocated to an external area of the BSA, the STA may be unable tocommunicate directly with other STAs included in the corresponding BSA.

The AP may correspond to, for example, a node-B, an evolved node-B(eNB), a base transceiver system (BTS), a femto BS, and a BS in adifferent wireless communication field.

A beacon frame corresponds to a management frame of the IEEE 802.11. Thebeacon frame may provide notification of a presence of a wirelessnetwork, and transmitted periodically so as to enable the STA performinga scanning to discover the wireless network and participate in thewireless network.

In the BSS, the AP may transmit the beacon frame periodically. When theSTA performing a scan receives the beacon frame, the STA may storeinformation associated with the BSS included in the beacon frame, moveto another channel, and record beacon frame information in the otherchannel. The STA receiving the beacon frame may store informationassociated with the BSS included in the received beacon frame and moveto a subsequent channel, thereby performing a scan in the subsequentchannel in an identical pattern.

The STA-1 220 and the STA-2 230 may be terminals that receive, in full,a signal transmitted in a 1 MHz mode and a signal transmitted in a 2 MHzmode, thereby demodulating the received signals.

For example, when the communication apparatus 210 transmits a signalusing the 2 MHz mode, the STA-1 220 may receive the signal and the STA-2230 may not receive the signal.

The 1 MHz mode may have the longest signal transmission distance. Thus,when the communication apparatus 210 transmits a signal using the 1 MHzmode, the STA-2 230 may also receive the signal. Accordingly, both aduplication mode using the 2 MHz mode as a base bandwidth and aduplication mode using the 1 MHz mode as a base bandwidth may berequired.

FIG. 3 is a diagram illustrating a configuration of a resourceallocation apparatus 300 in a WLAN system according to an exampleembodiment.

Referring to FIG. 3, the resource allocation apparatus 300 may include arestricted access bandwidth (RAB) interval determiner 320 and arestricted access window (RAW) setting unit 330. The resource allocationapparatus 300 may also include a state inspector 310 and a communicator340. According to an example embodiment, the resource allocationapparatus 300 may be included in an AP to operate.

The state inspector 310 may inspect a state of a BSS including the APand at least one STA. For example, the state inspector 310 may inspectan overlapping basic service set (OBS S) vulnerable state such as aperiodic mute interval. A state in which predetermined bandwidth modesare available may be affected by an OBSS only, aside from a case of anon-traffic indication map (TIM). The state inspector 310 may provideinformation associated with a state of the OBSS to the RAB intervaldeterminer 320. In a WLAN system, the STA may recognize whether data tobe transmitted to the STA is present based on a TIM element.

The RAB interval determiner 320 may determine an RAB interval based on abandwidth or a partial bandwidth among a plurality of bandwidths. TheRAB interval may indicate a restricted access zone on a frequency axis.A frequency domain to which the STA is allowed access may be determinedbased on the RAB interval. For example, only a data transmission lessthan or equal to a set RAB may be allowed, or only a data transmissiongreater than or equal to the set bandwidth may be allowed.

The RAB interval determiner 320 may determine the RAB interval based onthe information associated with the state of the OBSS provided by thestate inspector 310. The RAB interval determiner 320 may determine abandwidth or a partial bandwidth among a plurality of bandwidths basedon a state of the BSS. The RAB interval determiner 320 may determine theRAB interval based on the determined bandwidth or the determined partialbandwidth. For example, the RAB interval determiner 320 may determine apredetermined bandwidth or a predetermined partial bandwidth, forexample, a third 4 MHz BW from a left in a 16 MHz BSS operation, whichis determined to be clear, based on the information associated with thestate of the OBSS.

The RAB interval determiner 320 may periodically set a mute interval tomeasure interference from the OBSS, thereby identifying an availablebandwidth. To this end, an intended bandwidth plan may be set for allSTAs based on a transmission plan in a downlink (DL) transmission.Accordingly, a determination as to whether overlap is allowed may benecessary at each slot.

The RAW setting unit 330 may set an RAW of a time domain based on theRAB interval determined by the RAB interval determiner 320. The RAW mayindicate a restricted access interval on a time axis and also indicate apredetermined time interval in which predetermined STAs are allowedaccess. The RAW may determine the time domain in which the STA isallowed access. Access trials of the STAs may be distributed by settingthe RAW on the time axis.

The RAW setting unit 330 may set the RAW in the RAB interval and thus,control the STA to access in a predetermined time interval with respectto a data transmission with a predetermined bandwidth. For example,since the RAW is set to the RAB interval, only a data transmissioneither less than or equal to, or greater than or equal to the setbandwidth may be allowed to enter a time interval of the RAW. Thus, afrequency resource use rate may be improved in view of an overall BSS.

As an example, when the BSS is based on an 8 MHz mode, the RAB intervaldeterminer 320 may set a frequency interval of “4 MHz or more” on thefrequency axis, and allow entry of a data transmission of right 4 MHz,left 4 MHz or 8 MHz. In this instance, the RAW setting unit 330 may setthe RAW with respect to the RAB interval determined on the frequencyaxis, and allow the entry of the data transmission of right 4 MHz, left4 MHz or 8 MHz in a time interval corresponding to the set RAW.

As another example, when the BSS is based on a 16 MHz mode, the RABinterval determiner 320 may set a frequency interval of “2 MHz or less”on the frequency axis, and allow entry of a data transmission of 2 MHzor 1 MHz. In this instance, the RAW setting unit 330 may set the RAWwith respect to the RAB interval determined on the frequency axis, andallow the entry of the data transmission of 2 MHz or 2 MHz in a timeinterval corresponding to the set RAW.

The RAW setting unit 330 may set a priority of the RAW based on abandwidth used by the STA. The RAW setting unit 330 may group the STAsbased on the priority set for the RAW and assign the grouped STAs. TheRAW setting unit 330 may set the RAW with respect to each of the STAs ina beacon interval based on the priority of the RAW. The RAW setting unit330 may set the RAW with respect to each of the STAs such that STAsusing a relatively large bandwidth may be temporally prioritized in thebeacon interval.

The communicator 340 may transmit, to the STA, information associatedwith the RAB interval and information associated with the RAW. When thecommunicator 340 transmits data to the STA in DL data delivery, data maybe aligned on a slot-by-slot basis. The communicator 340 may perform aplurality of bandwidth transmissions concurrently without overlapping onthe frequency axis. The communicator 340 may perform a multi-channeltransmission on slot-by-slot basis, thereby improving frequencyefficiency.

For each instance in which a slot is initiated, the communicator 340 maytransmit, to the STA, the information associated with the RAB intervalusing a duplication mode frame or a synchronized (sync) frame. Thecommunicator 340 may provide notification of a frequency range availablefor a corresponding slot in the duplicated form of a frame bybroadcasting. Alternatively, the communicator 340 may supply acorresponding function to the sync frame. For example, the communicator340 may store the information associated with the RAB interval orinformation associated with the frequency range available for thecorresponding slot in a scrambling seed or a basic unit of signal (SIG)field in the duplication mode frame, thereby transmitting the storedinformation to the STA.

For effective control of a request to send (RTS)/clear to send (CTS) ina slot or the RAW, a process of identifying a slot-based or an RAW-basedavailable frequency range may be performed in advance through a sequenceexchange of RTS (AP)=>CTS (from a representative STA or allocated STAs).

Irrespective of whether the RTS/CTS is performed based on a slot or theRTS/CTS is performed between links, a process of decreasing may beconducted in a bandwidth of each of the links based on a previouslyintended plan. Thus, an occurrence of overlapping between the BWs to beused, caused by an RTS/CTS exchange, may be prevented.

In a case of an 8 MHz transmission including a primary 1 MHz, aprimary/secondary channel allocation scheme of 802.11 ac, whichinflexibly determines a primary 1 MHz, a primary 2 MHz, and a primary 4MHz, may need to be flexible such that, for example, the DL transmissionwith a secondary 40 MHz is allowed to be performed on a predeterminedSTA.

When a response to an instantaneous change in an OBSS vulnerable stateis required, the resource allocation apparatus 300 may enable the RABinterval to be initiated at every point in time during a beacon intervaland separate indication information, for example, a list ofcorresponding STAs may be provided at a start time. For a case in whichthe OBSS vulnerable state changes infrequently, providing notificationto a beacon may be necessary. The bandwidth to be used may be changed toanother, based on an unexpected instantaneous state. In this instance,relocating to an unscheduled time interval assigned to another bandwidthis required.

FIG. 4 is a diagram illustrating a configuration of a communicationterminal 400 in a WLAN system according to an example embodiment.

Referring to FIG. 4, the communication terminal 400 may include acommunicator 410 and a controller 420.

The communicator 410 may receive information associated with an RABinterval and information associated with an RAW from an AP. A frequencydomain in which a data transmission is allowed may be determined basedon the RAB interval. The RAW may indicate a time domain in which thedata transmission is allowed.

For example, the communicator 410 may extract the information associatedwith the RAB interval from a synch frame or a duplication mode framereceived from the AP at each instance a slot is initiated. Thecommunicator 410 may extract the information associated with the RABinterval or information associated with an available frequency rangefrom a scrambling seed or a basic unit of SIG field in a duplicationmode frame.

The controller 420 may determine, based on the RAB interval, thefrequency domain allowing an access, and determine whether communicationis available in the determined frequency domain. The RAB interval may beprovided in a form of a bandwidth or a partial bandwidth. The RABinterval may determine the frequency domain in which a data transmissionis allowed. For example, only a data transmission less than or equal toa set RAB may be allowed, or only a data transmission greater than orequal to the set RAB may be allowed.

When communication is available in the frequency domain determined basedon the RAB interval, the communicator 410 may transmit data in the timedomain determined based on the RAW. The RAW may indicate the time domainin which the data transmission is allowed. The frequency domaindetermined based on the RAB interval may correspond to one of afrequency domain less than or equal to a bandwidth set based on the RABand a frequency domain greater than or equal to the bandwidth set basedon the RAB. Based on the RAB interval and the RAW, the communicator maytransmit the data in a predetermined bandwidth and a predetermined timedomain. For example, a data transmission either less than or equal to,or greater than or equal to the bandwidth set based on the RAB intervalmay be performed in the time domain determined based on the RAW.

FIGS. 5 and 6 are diagrams illustrating examples of a resourceallocation method according to an example embodiment.

Referring to FIG. 5, an RAW is set in a WLAN system in lieu of an RABinterval. Accordingly, STAs or communication terminals may transmit datain predetermined time intervals 510, and 520 determined based on the RAWirrespective of a bandwidth or a channel to be used.

Referring to FIG. 6, in a WLAN system, an RAB interval is determinedwith respect to each STA, and an RAW is set based on the determined RABinterval. Each STA may transmit data in a time domain determined basedon the RAW in a bandwidth or a channel allocated to the STA.

For example, an STA 1 may transmit data in a time domain of a timeinterval 1 610 in a frequency domain of a channel (CH) 1. An STA 2 maytransmit data in a time domain of a time interval 2 620 in a frequencydomain of a CH 2. An STA 3 may transmit data in a time domain of a timeinterval 3 630 in a frequency domain of a CH 3. An STA 4 may transmitdata in a time domain of a time interval 4 640 in a frequency domain ofa CH 4. Subsequently, the STA 1, the STA 2, the STA 3, and the STA 4 maytransmit data in time domains of time intervals 650, 660, 670, and 680in CHs in an identical pattern, respectively.

FIGS. 7A and 7B are diagrams illustrating examples of configuring aduplication mode frame according to an example embodiment.

FIG. 7A illustrates a 2 MHz duplication mode frame.

In this instance, the 2 MHz duplication mode frame may include a basicframe 710 and a duplication frame 720 having a phase different from aphase of the basic frame 710 by 90 degrees (°). Referring to FIG. 7A, aduplication mode frame transmission may include an operation oftransmitting a frame and then shifting a phase of the same frame by 90°based on a DC tone and transmitting the phase-shifted frame, through twobandwidths, respectively.

For example, a process of transmitting the duplication mode frame mayinclude an operation of transmitting a basic frame through a third bandwhile simultaneously transmitting a duplication frame through a fourthband.

Accordingly, a receiver receiving a duplication mode frame may performdemodulation by receiving a frame received from any one of the thirdband and the fourth band.

The basic frame 710 of FIG. 7A may be provided in a same structure as astructure of the 1 MHz mode frame. The basic frame 710 may include ashort training field (STF), a long training field (LTF), and a SIGfield.

The SIG field of the 1 MHz mode frame may be provided in a structure inwhich information associated with a bandwidth is omitted.

When the duplication mode frame is configured based on a bandwidth of 1MHz, inserting information defining a bandwidth may be required. Forexample, bandwidth information may be inserted using a portion of bitsamong four bits defined as a reserved bit in an SIG. In this instance,the bandwidth information may refer to information associated with abandwidth of a frequency axis used in the example of FIG. 7A. Also, thebandwidth information may be defined using a portion of lower bits of ascrambler sheet included in a service field.

Three bits may be required to divide a bandwidth into 1 MHz, 2 MHz, 4MHz, 8 MHz, and 16 MHz and subsequently identify the divided bandwidths.

Accordingly, a frame structure of a first bandwidth may be provided in astructure in which information associated with a multi-bandwidth isomitted, and a basic frame generated based on the first bandwidth mayinclude information associated with the multi-bandwidth in a SIG fieldor a service field.

FIG. 7B illustrates a 4 MHz duplication mode frame.

The 4 MHz duplication mode frame may include a basic frame 710 and threeduplication frames having phases different from a phase of the basicframe 710 by 180°.

As illustrated in FIG. 6, a null data packet (NDP) type short CTSmessage may be generated using a bandwidth of 1 MHz as a basic unit. Inthis instance, the NDP type short CTS message may be provided in a formof FIG. 7B excluding fields subsequent to an LTF 2.

FIGS. 8A and 8B are diagrams illustrating examples of configuring aduplication mode frame according to another example embodiment.

FIG. 8A illustrates a 4 MHz duplication mode frame.

In this instance, the 4 MHz duplication mode frame may include a basicframe 810 and a duplication frame 820 having a phase different from aphase of the basic frame 810 by 90°. Referring to FIG. 8A, transmissionof a duplication mode frame may be performed by transmitting a frame andthen shifting a phase of the same frame by 90° based on a (DC) tone andtransmitting the phase-shifted frame, through two bands, respectively.

For example, a process of transmitting the duplication mode frame mayinclude an operation of transmitting a basic frame through a first bandand simultaneously transmitting a duplication frame through a secondband.

Accordingly, a reception end receiving a duplication mode frame mayperform demodulation by receiving a frame received from any one of thefirst band and the second band.

As illustrated in FIG. 8A, the basic frame 810 may be provided in anidentical structure to a structure of the 2 MHz mode frame. The basicframe 810 may include an STF, an LTF, and an SIG field.

FIG. 8B illustrates an 8 MHz duplication mode frame.

The 8 MHz duplication mode frame may include a basic frame 810 and threeduplication frames 830 having a phase different from a phase of thebasic frame 810 by 180°.

Four frames included in the 8 MHz duplication mode frame may besimultaneously transmitted through four separate bandwidths.

Accordingly, a reception end receiving a duplication mode frame mayperform demodulation or detection although only one frame is receivedamong the aforementioned four frames.

Although not shown in FIG. 8B, a 16 MHz duplication mode frame may beprovided in a structure in which the 8 MHz duplication mode frame isrepeated twice on a frequency axis.

The structure of the duplication mode frame illustrated in FIGS. 8A and8B may be used to transmit an RTS message and an “NDP type short CTSmessage” in which a data portion is not included.

FIG. 9 is a flowchart illustrating an operation of a resource allocationmethod in a WLAN system according to an example embodiment.

In operation 910, a resource allocation apparatus may inspect a state ofa BSS including an AP and at least one STA. For example, the resourceallocation apparatus may inspect an OBSS vulnerable state such as aperiodical mute interval.

In operation 920, the resource allocation apparatus may determine an RABinterval based on a bandwidth or a partial bandwidth among a pluralityof bandwidths. The RAB interval may indicate a restricted accessinterval on a frequency axis. A frequency domain to which the STA isallowed access may be determined based on the RAB interval. For example,only a data transmission less than or equal to a set RAB may be allowed,or only a data transmission greater than or equal to the set bandwidthmay be allowed.

The resource allocation apparatus may determine the RAB interval basedon the information associated with a state of the OBSS. The resourceallocation apparatus may determine a bandwidth or a partial bandwidthamong a plurality of bandwidths based on a state of the BSS. Theresource allocation apparatus may determine the RAB interval based onthe determined bandwidth or the determined partial bandwidth. Theresource allocation apparatus may periodically set a mute interval tomeasure interference from the OBSS, thereby identifying an availablebandwidth.

In operation 930, the resource allocation apparatus may set an RAW of atime domain based on the determined RAB interval. The RAW may indicate arestricted access interval on a time axis and also indicate apredetermined time interval in which predetermined STAs are allowedaccess. The RAW may determine the time domain in which the STA isallowed access.

The resource allocation apparatus may set the RAW in the RAB intervaland thus, control the STA to access in a predetermined time intervalwith respect to a data transmission with a predetermined bandwidth. Forexample, since the RAW is set to the RAB interval, only a datatransmission either less than or equal to, or greater than or equal tothe set bandwidth may be allowed to enter a time interval of the RAW.Thus, a frequency resource use rate may be improved in view of anoverall BSS.

The resource allocation apparatus may set a priority of the RAW based ona bandwidth used by the STA. The resource allocation apparatus may groupthe STAs based on the priority of the RAW and assign the grouped STAs.The resource allocation apparatus may set the RAW with respect to eachof the STAs such that STAs using a relatively large bandwidth may betemporally prioritized in the beacon interval.

In operation 940, the resource allocation apparatus may transmitinformation associated with the RAB interval and information associatedwith the RAW to the STA. When the resource allocation apparatustransmits data to the STA in DL data delivery, data may be aligned on aslot-by-slot basis. The resource allocation apparatus may perform aplurality of bandwidth transmissions concurrently without overlap on thefrequency axis. For each instance at which a slot is initiated, theresource allocation apparatus may transmit, to the STA, the informationassociated with the RAB interval using a duplication mode frame or async frame. The resource allocation apparatus may store informationassociated with an available frequency range in a scrambling seed or abasic unit of SIG field in the duplication mode frame.

FIG. 10 is a flowchart illustrating an operation of a communicationmethod in a WLAN system according to an example embodiment.

In operation 1010, a communication terminal may receive informationassociated with an RAB interval and information associated with an RAWfrom an AP. A frequency domain in which a data transmission is allowedmay be determined based on the RAB interval. The RAW may indicate a timedomain in which the data transmission is allowed. The communicationterminal may extract the information associated with the RAB intervalfrom a synch frame or a duplication mode frame received from the AP ateach instance of a slot initiation.

In operation 1020, the communication terminal may determine thefrequency domain allowing an access, based on the RAB interval, anddetermine whether communication is available in the determined frequencydomain.

In operation 1030, when communication is available in the frequencydomain determined based on the RAB interval, the communication terminalmay transmit data in the time domain determined based on the RAW. Thefrequency domain determined based on the RAB interval may correspond toone of a frequency domain less than or equal to a bandwidth set based onthe RAB and a frequency domain greater than or equal to the bandwidthset based on the RAB. Based on the RAB interval and the RAW, thecommunication terminal may transmit the data in a predeterminedbandwidth and a predetermined time domain.

The method according to the above-described embodiments may be recordedin non-transitory computer-readable media including program instructionsto implement various operations embodied by a computer. The media mayalso include, alone or in combination with the program instructions,data files, data structures, and the like. Examples of non-transitorycomputer-readable media include magnetic media such as hard disks,floppy discs, and magnetic tape; optical media such as CD ROM discs andDVDs; magneto-optical media such as optical discs; and hardware devicesthat are specially configured to store and perform program instructions,such as read-only memory (ROM), random access memory (RAM), flashmemory, and the like. Examples of program instructions include bothmachine code, such as produced by a compiler, and files containinghigher level code that may be executed by the computer using aninterpreter. The described hardware devices may be configured to act asone or more software modules in order to perform the operations of theabove-described embodiments, or vice versa.

Although a few embodiments of the present invention have been shown anddescribed, the present invention is not limited to the describedembodiments. Instead, it would be appreciated by those skilled in theart that changes may be made to these embodiments without departing fromthe principles and spirit of the invention, the scope of which isdefined by the claims and their equivalents.

1. A method for supporting channel access by an access point (AP), themethod comprising: generating an information element indicating a set ofchannels and times allowed for channel access; and transmitting a beaconframe including the information element, wherein a first subset ofchannels is allowed for channel access during a first time periodindicated by the information element, and wherein a second subset ofchannels is allowed for channel access during a second time periodindicated by the information element.
 2. The method according to claim1, wherein a first station (STA) is allowed to operate on the firstsubset of channels during the first time period, and a second STA isallowed to operate on the second subset of channels during the secondtime period.
 3. The method according to claim 1, wherein the first timeperiod does not overlap with the second time period.
 4. The methodaccording to claim 1, wherein the first subset of channels is differentfrom the second subset of channels.
 5. The method according to claim 1,wherein at least one of the first subset of channels or the secondsubset of channels does not include a primary channel for a basicservice set (BSS) operated by the AP.
 6. The method according to claim1, wherein at least one of the first time period or the second timeperiod is set in a periodic manner.
 7. A method for channel access by astation (STA), the method comprising: receiving, from an access point(AP), a beacon frame including an information element, the informationelement indicating a set of channels and times allowed for channelaccess; and transmitting or receiving on a subset of channels which isallowed for channel access during a time period indicated by theinformation element, wherein a first subset of channels is allowed forchannel access during a first time period indicated by the informationelement, and wherein a second subset of channels is allowed for channelaccess during a second time period indicated by the information element.8. An apparatus of an access point (AP) for supporting channel access byan access point (AP), the apparatus comprising: a transceiver; and aprocessor, wherein the processor is configured to: generate aninformation element indicating a set of channels and times allowed forchannel access; and cause the transceiver to transmit a beacon frameincluding the information element, wherein a first subset of channels isallowed for channel access during a first time period indicated by theinformation element, and wherein a second subset of channels is allowedfor channel access during a second time period indicated by theinformation element.